Old but incredibly thorough studies of all measurable aspects of divorce in the U.S.: They don't make 'em like this anymore.

Really. Nowadays relatively little information about divorces is collected; far less is aggregated and reported; and hardly any of it is actually studied, compared, correlated, etc. But from the beginning it was not so. The CDC's web site maintains these reports, which include analyses that are still somewhat relevant because nothing like them has been done in recent decades. They stand as testimony to the decline of the CDC's National Center for Health Statistics.

100 Years of Marriage and Divorce Statistics, United States, 1867-1967

Divorces and Divorce Rates, United States: Analysis of divorce statistics for the early 1970’s, including specific divorce rates by various characteristics, based on population data from the 1970 census, and trend data through 1976.